Rare blood group called Dantu may provide protection against deadly malaria, study shows

As per the 2018 World Malaria Report by the World Health Organisation (WHO), India and countries in sub-Saharan Africa account for 85 percent of the world’s malaria cases.

Malaria causes approximately 435,000 deaths every year globally,  61 percent of which are children under five.

Malaria is a disease caused by the bite of the female Anopheles mosquito which carries Plasmodium parasites.

It usually presents with fever, chills and headache and can be life-threatening if not treated.

The vaccine for malaria is not effective enough as it provides only 35 percent protection.

However, scientists from the Wellcome Sanger Institute, along with the University of Cambridge and the KEMRI-Wellcome Trust Research Programme, Kenya, have found that people with a rare blood group, Dantu, may have protection against the malaria parasite, Plasmodium falciparum.

Apart from the blood group system that we normally use (ABO blood group system) there are 34 other blood group systems including the MNS blood group systems. Blood groups are determined by the antigens (proteins) present on the surface of the red blood cells.

The MNS blood group antigens were discovered in the 1920s. Dantu is a type of blood group seen in the MNS blood group system.

Examining blood group Dantu against malaria

The red blood cells (RBCs) have specific proteins on them called glycophorins. Glycophorin A (GYPA) and Glycophorin B (GYPB) are two of the many receptors that Plasmodium, the causative agent of malaria, uses to enter into healthy cells.

Both these glycophorins (coded by the genes of the same name) also carry the antigenic determinants of MN and Ss blood groups.

The GYPA and GYPB genes are present on the same chromosome and they rearrange in various ways to make specific antigens in the MNS blood group. Dantu antigen is one such hybrid of GYPA and GYPB gene.

The latest study found that people with GYPB-A hybrid gene are less likely to develop severe complications of malaria and the sequence of this particular hybrid was found to be that of Dantu antigen.

To examine the effects of Dantu blood group, scientists collected red blood cell samples from 42 healthy children in Kenya, who had one, two or zero copies of the Dantu gene. These red blood cells were then exposed to the malaria parasite in the laboratory.

The samples were examined using multiple tools along with time-lapse video microscopy, which identified the point where the parasite invasion was impaired.

Results of the study

The results of the study showed that the red blood cell samples that had the Dantu gene formed cells with higher surface tension, which can be visualised as a drum with tighter skin. At a particular point, the malaria parasites were unable to enter the cells, thus their lifecycle halted in the blood.

Dr Silvia Kariuki, from the KEMRI-Wellcome Trust Research Programme, explained that malaria parasites work in a ‘lock-and-key' manner to enter the human red blood cells. The Dantu gene increases the tension of the red blood cell surface, thus inhibiting the entry of the parasite. So, in a way, the virus still has the key to the lock, but the door gets extremely heavy to open.

The scientists explained that the Dantu blood group has a chimeric protein (protein structure formed after the fusion of two proteins) on the surface of red blood cells, which increases the tension of the cells.

It was discovered that people who had one copy of the Dantu gene had 40 percent protection against malaria and those with two copies of Dantu gene had 70 percent protection against the disease.

Future plans

Scientists stated that the surface tension of human red blood cells naturally increases as the cells age. The normal lifespan of a red blood cell is 90 days. They believe that by designing the drugs that naturally increase the surface tension of red blood cells, we will be able to prevent malaria infection or reduce its severity.

For more information, read our article on malaria.

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